Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
Porous membrane filtration systems require regular backwashing of the membranes to maintain filtration efficiency and flux while reducing transmembrane pressure (TMP) which rises as the membrane pores become clogged with impurities. Typically, during the backwash cycle the impurities are forced out of the membrane pores and/or scoured from the membrane surfaces into the feed tank or cell by one or more of pressurised gas, gas bubbles, liquid or a mixture thereof. The liquid containing impurities and deposits from the membranes is then drained or flushed from the tank.
Further, in filtration systems employing gas bubble scouring of the membranes it has been found advantageous to confine the bubbles as much as possible in the region of the membranes to assist with the scouring process.
Minimising the footprint of filtration systems is also desirable in terms of space eventually occupied by the filtration plant. Compact systems have lower cost, less waste volume, lesser impact on the environment and are more acceptable to the market.
It would be desirable to be able to provide the advantages of such systems to known systems which have been initially designed and manufactured without such cleaning and backwash processes in mind. Further it is desirable to simplify the manifolding and piping required to provide gas and liquid to the membrane modules during the filtration, backwashing and cleaning processes.